The effects of reaction temperature, methane partial pressure, and reaction period on growing single-walled carbon nanotubes (SWCNTs) are demonstrated in the present study. Simple methane CVD is carried out using a homemade iron nanoparticles catalyst. The iron nanoparticles are prepared by spin-coating a colloidal mixture of iron(III) nitrate, PEG-400, and absolute ethanol on silicon wafers. The experimental results show that the effects of all three reaction parameters studied, on the morphology and the topography of the SWCNT arrays, are significant. There is no evidence showing that the diameter of SWCNTs is correlated with these three reaction parameters.